The present invention is related to filter systems in general and particularly to such systems for achieving a very high degree of removal of suspended particles from a fluid containing the same.
Fluids are frequently encountered which are highly desirable or useful, but which contain suspended particles which are difficult, expensive or time consuming to remove.
Many present methods of filtration rely often upon pressure to achieve rapid removal of particulates. This requires a high pressure pump, piping, and containers. As a result, leakage, valving, and possible line ruptures constitute an expensive nuisance.
Gravity systems are also employed in which the above mentioned high pressure problems are avoided. However, gravity systems are usually extremely slow. For example, "problem liquids" which are quite viscous, or liquids containing extremely fine suspended matter are not easily filtered by gravity systems. There remains a need for a filtration system by which "problem liquids" and other fluids may be quickly and easily filtered.
A gasket arrangement for purification apparatus is disclosed by Croopnick et al in U.S. Pat. No. 4,132,649. The apparatus disclosed includes a stack of disk shaped filtering membranes and a stack of separating gaskets. The gaskets are fitted between successive membranes to seal the membranes and to space the membranes apart for filtration purposes. The primary thrust of the Croopnick patent is a different and improved way of supporting and separating the membrane packs and the gasket packs.
An external high pressure pump and piping system are required by the Croopnick device to force liquid through the system for purification. The membrane and gasket assembly may be rotated in its housing in order to produce centrifugal forces that aid flow of the fluid. It is pointed out, however, that the rotational energy and resulting centrifugal forces is merely an "aid" to fluid flow. The system still requires an external high pressure feed pump and inlet piping to produce flow through the filtering assembly. High compressive forces are required to hold the purification apparatus together and to minimize leakage.
Croopnick includes two liquid outlets. A permeate outlet is provided to discharge filtered liquid. A concentrate outlet is also provided through which very impure liquid is delivered. The filtering arrangement therefore does not function to entrap and hold all particulate material from the fluid. Instead, collected particulates and a portion of the fluid are collected in a concentrated form. The present dynamic liquid filter system provides its own pumping action and thoroughly cleans the input fluid without collection of a concentrated mixture of the fluid and of particulates. The system is therefore a "one pass" system that will operate quickly and effectively to produce the desired results of fluid filtering at the approximate speed of high pressure systems and with the thorough filtering capability of both high pressure and gravity filtering systems.